Method and apparatus for recovering and purging refrigerant

ABSTRACT

Apparatus for recovering refrigerant from a refrigeration system having a high pressure liquid side and a low pressure vapor side comprises a storage receptacle for receiving recovered refrigerant, a liquid flow circuit for recovering liquid from the high pressure side of the system, a vapor flow circuit for recovering vapor from the low pressure side of the system, and a vapor feedback flow circuit from the receptacle to the inlet side of a vapor reducing section of the vapor flow circuit. The apparatus is operable in a liquid recovery mode and in a vapor recovery mode, and an arrangement for automatically purging non-compressible gases from liquid refrigerant is provided in the vapor flow circuit on the downstream side of the vapor reducing section thereof. During a liquid recovery operation, vapor is fed back from the storage receptacle to the inlet side of the vapor reducing section and non-condensable gas in the liquid refrigerant flowing therefrom is separated from the liquid prior to return of the liquid refrigerant to the storage receptacle. During a vapor recovery operation, the apparatus is operable to shift back to the liquid recovery mode in response to a high pressure in the storage receptacle, whereby vapor in the receptacle is fed back and reduced to a liquid from which non-condensable gas is removed prior to return of the liquid to the receptacle. Gas removed from the liquid refrigerant is accumulated and periodically exhausted to atmosphere.

BACKGROUND OF THE INVENTION

The present invention relates to the art of refrigerant recovery and,more particularly, to an improved method and apparatus for recoveringrefrigerant from a refrigerating system having a high pressure liquidside and a low pressure vapor side and purging gas from the refrigerantduring the recovery thereof.

The present invention finds particular utility in conjunction withrefrigerant recovering apparatus operable in a liquid recovery mode andin a vapor recovery mode and which, when operating in the vapor recoverymode, is responsive to an unacceptably high pressure and thustemperature in the refrigerant recovery receptacle to disconnect thesource of vapor being recovered from vapor reducing components of theapparatus and to circulate vapor in the recovery receptacle to the vaporreducing components for reduction to a liquid which is returned to therecovery receptacle, thus to reduce the pressure and temperature thereinto acceptable levels. At the same time, as will become apparenthereinafter, the invention is applicable to refrigerant recovery methodsand apparatus other than those including an arrangement for cooling therecovery receptacle during the vapor recovery operation.

A refrigerant recovery unit of the foregoing character is available fromRidge Tool Company of Elyria, Ohio under the latter's productdesignation Model RS-200 which is a portable unit for recovering avariety of refrigerants from air conditioning and other refrigerationsystems having a high pressure liquid side and a low pressure vapor sidefrom which refrigerant must be withdrawn in a recovery operation. Thisunit includes a casing enclosing the refrigerant recovery componentsincluding a compressor and condenser, flow lines and valving, andelectrical circuitry which controls operation of the unit. Therefrigerant recovery components provide liquid and vapor flow circuitshaving inlet ends selectively connectable through flexible hoses to thehigh pressure liquid and low pressure vapor sides of a refrigerationsystem from which refrigerant is to be recovered. The flow circuits haveoutlet ends connected to the refrigerant storage tank through a flexiblehose. The refrigerant recovery components further include a vapor feedback circuit connectable to the storage tank through a flexible hose andby which vapor in the storage receptacle is adapted to be fed back toand through the vapor reducing components for return to the storagereceptacle as a liquid. The electrical control circuit provides for theunit to be selectively operated in the liquid recovery mode and in thevapor recovery mode.

In the liquid recovery mode, liquid refrigerant from the refrigerationsystem is drawn directly into the storage receptacle, bypassing thevapor reducing components, and vapor in the storage receptacle is fedback and reduced in the foregoing manner and returned to the receptacleas a liquid. In the vapor mode, the vapor feedback circuit is closed andvapor is drawn from the refrigeration system and is reduced and pumpedto the storage receptacle as a liquid. During vapor recovery, thepressure and thus the temperature in the storage receptacle can becomeundesirably high and, the pressure in the storage receptacle ismonitored and, in response to an undesirably high pressure indicating anundesirably high temperature, the unit shifts to the liquid recoverymode whereby the vapor input from the refrigeration system to the vaporreducing components is blocked and the vapor feedback circuit is opened.This results in feed back of vapor from the receptacle to the vaporreducing components as described above, thus to reduce the pressure inand cool the storage receptacle. When the pressure is reducedsufficiently, the unit shifts back to the vapor recovery mode, wherebythe feedback circuit is again closed and the input of vapor from therefrigeration system is recommenced so as to continue the vapor recoveryoperation. While it would be possible to discontinue operation of theunit during vapor recovery in response to an undesirably hightemperature in the storage receptacle and then recommence the recoveryoperation when the temperature subsides sufficiently, the vapor feedbackarrangement advantageously provides for minimizing the vapor recoverytime by automatically providing a cooling function in conjunction withoperation of the unit.

In connection with operating a refrigerant recovery unit of theforegoing character, it is of course necessary to purge air from theflexible hoses and from the liquid and vapor flow circuits prior tostarting a recovery operation. Such purging is done manually and is timeconsuming. In this respect, the flexible hoses for connecting the highand low pressure sides of the refrigeration system with the recoveryunit and for connecting the refrigerant storage receptacle with the unitinclude in-line valves to minimize the escape of refrigerant duringstart-up and shut-down of the equipment, and the storage receptacle hasshut-off valves for the liquid and vapor line connections thereto.Moreover, as is well known, a refrigerating system from whichrefrigerant is to be recovered has service valves associated with eachof the high pressure liquid and low pressure vapor sides of the system.Thus, there are 8 valves which have to be opened and closed and severalhose connections which have to be loosened and tightened in connectionwith purging air from the equipment prior to initiating the refrigerantrecovery operation. Moreover, when the unit is operating in the liquidrecovery mode, or is shifted to the latter mode during vapor recovery asdescribed above in response to an undesirably high pressure in thestorage receptacle, the liquid flowing back to the receptacle from thevapor reducing components flows through a capillary expander.Non-condensable gases in the liquid, primarily air, cannot easily passthrough the capillary tube and, thus, back up and accumulate in thecondenser. This reduces the cooling capacity of the feedback flowcircuit and thus increases the time required to lower the pressure inthe storage receptacle to the level at which the unit shifts back to thevapor recovery mode. This in turn increases the overall time required tocomplete the vapor recovery operation.

SUMMARY OF THE INVENTION

In accordance with the present invention, refrigerant recovery apparatushaving liquid flow circuitry, vapor flow circuitry for reducing vapor toliquid, and a vapor feedback circuit for vapor in the refrigerantrecovery storage receptacle to be reduced and returned to the receptacleas a liquid is provided with a gas purging arrangement. The purgingarrangement is between the vapor reducing section of the vapor flowcircuit and the refrigerant storage receptacle and is adapted to removegas from liquid refrigerant flowing from the vapor reducing section tothe receptacle. The vapor feedback circuit is open to the vapor reducingsection at least during operation of the apparatus to recover liquidfrom the high pressure liquid side of a refrigeration system and,preferably, is adapted to be connected with the vapor reducing sectionin response to an unacceptably high pressure in the storage receptacleduring a vapor recovery operation so as to achieve cooling and areduction of pressure in the receptacle so as to optimize the timerequired to achieve completion of a vapor recovery operation. In anyevent, the gas purging arrangement eliminates the need to manually purgethe apparatus prior to initiating a refrigerant recovery operation and,in the preferred arrangement, additionally serves to minimize the timerequired to achieve completion of a vapor recovery operation by avoidingthe backup of non-condensable gas into the vapor reducing section of thevapor recovery circuit. The gas removed from the liquid refrigerant isaccumulated and exhausted to atmosphere and, preferably, the operationof the gas purging arrangement in this respect is automatic through apurging control circuit which is activated when the apparatus is in theliquid recovery mode. If the apparatus is operable during vapor recoveryto achieve vapor feedback from the storage receptacle for cooling andreducing the pressure in the receptacle as described above, the purgecontrol circuit is activated during such feedback operation so as toenable the exhausting of purged gas to atmosphere.

Preferably, a gas purging arrangement according to the inventionincludes a chamber arrangement providing for non-condensable gas in theliquid refrigerant to gravitate upwardly therefrom into an accumulatingor storage space from which the gas is exhausted to atmosphere.Preferably, the quantity of accumulated gas is monitored and, inresponse to the accumulation of a pre-determined quantity, the gas isreleased to atmosphere. Still further in accordance with a preferredarrangement, the exhausting of accumulated gas to atmosphere is periodicand is controlled in part by a timer in the purge control circuit whichhas a repeating time cycle including purge and non-purge modes,respectively enabling and disabling the exhaust of gas to atmosphere.Thus, if the timer is activated and a pre-determined quantity of gas hasaccumulated in the chamber arrangement, the accumulated gas will beexhausted during each purge portion of successive timer cycles. Theremoval of gas from the liquid refrigerant flowing from the vaporreducing section advantageously eliminates or minimizes the problemreferred to hereinabove with regard to the backup of gas into the vaporreducing section of the vapor flow circuit during a vapor recoveryoperation.

It is accordingly an outstanding object of the present invention toprovide refrigerant recovery apparatus operable in a liquid recoverymode and in a vapor recovery mode with an arrangement for purging gasfrom liquid refrigerant flowing to a refrigerant recovery storagereceptacle from a vapor reducing section of the apparatus.

Another object is the provision of refrigerant recovery apparatus of theforegoing character wherein the gas purging arrangement eliminates theneed to manually pre-purge the apparatus prior to initiating arefrigerant recovery operation.

A further object is the provision of refrigerant recovery apparatus ofthe foregoing character wherein the purging arrangement is operable inthe liquid recovery mode and can be operated during the vapor recoverymode to minimize the vapor recovery time.

Yet another object is the provision of refrigerant recovery apparatus ofthe foregoing character wherein the purging arrangement is activatedwhen the apparatus is in the liquid recovery mode and is actuated toexhaust gas to atmosphere upon the accumulation of a pre-determinedquantity of gas.

Still a further object is the provision of refrigerant recoveryapparatus of the foregoing character wherein the purging arrangement isadapted to be activated when the apparatus is operating in the vapormode in response to the existence of an undesirable condition in therecovery receptacle.

Another object is the provision of refrigerant recovery apparatus of theforegoing character wherein the gas purging arrangement provides for theseparation of gas from liquid refrigerant by gravitation of the gas intoan accumulating chamber in which the quantity of accumulated gas ismonitored and from which accumulated gas is periodically exhausted toatmosphere.

A further object is the provision of a method and apparatus forrecovering refrigerant from a refrigeration system and for purging gasfrom the refrigerant being recovered and during the recovery operation,such that manual pre-purging of the recovery apparatus is not necessaryand such that the overall recovery operation is more efficient and lesstime consuming than heretofore possible.

BRIEF DESCRIPTION OF THE DRAWING

The foregoing objects, and others, will in part be obvious and in partpointed out more fully hereinafter in conjunction with the writtendescription of a preferred embodiment of the invention illustrated inthe accompanying drawing in which:

FIG. 1 is a liquid flow diagram for a prior art refrigerant recoverysystem;

FIG. 2 is a wiring diagram for the system illustrated in FIG. 1;

FIG. 3 is a liquid flow diagram similar to FIG. 1 and including a gaspurging arrangement in accordance with the present invention; and

FIG. 4 is a wiring diagram similar to FIG. 2 and including a controlcircuit for the purging arrangement.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring now in greater detail to the drawings, wherein the showingsare for the purpose of illustrating a preferred embodiment of theinvention only and not for the purpose of limiting the same, FIGS. 1 and2 schematically illustrate prior art apparatus for recoveringrefrigerant from an air conditioning or refrigeration system 10,hereinafter referred to collectively as a refrigeration system, andwhich system has a high pressure liquid side and a low pressure vaporside from which refrigerant is to be recovered and which sides arerespectively assessable through service valves 12 and 14. Therefrigerant recovery apparatus includes a recovered refrigerant storagereceptacle 16 having a liquid refrigerant inlet line 18 and a vaporoutlet line 20 opening thereunto through corresponding manually operatedshut-off valves 22 and 24. As will be explained in greater detailhereinafter, line 18 provides a passageway for the flow of liquidrefrigerant 26 into receptacle 16, and line 20 provides a passageway forvapor 28 above liquid 26 to flow out of the receptacle. The refrigerantrecovery apparatus further includes liquid and vapor flow circuitry 30as shown in FIG. 1 and an electrical circuit 32 therefor as shown inFIG. 2. The component parts of circuits 30 and 32 are housed in a casing34 which, while not shown, provides for the component parts of theapparatus therein to be portable and carried to the location ofrefrigeration system 10 together with receptacle 16 which is separablefrom the component parts in casing 34.

Liquid and vapor circuitry 30 includes a liquid flow circuit 36, a vaporflow circuit 38, and a vapor feedback circuit 40. Liquid flow circuit 36includes a flow line 42 having an inlet end 44 connected to a systeminlet line 46 through a sight glass 48 which serves the purpose setforth hereinafter. Inlet line 46 has an outer end 50 adjacent theexterior of casing 34 for connecting the recovery apparatus torefrigeration system 10 as set forth more fully hereinafter. Flow line42 has an outlet end 52 connected to a system outlet line 54 which hasan outer end 56 adjacent the exterior of casing 34 for connecting outletline 54 with storage tank 16 as set forth hereinafter. A check valve 58is provided in flow line 42 adjacent inlet end 44 thereof for precludingthe backflow of liquid refrigerant through inlet line 46.

Vapor flow circuit 38 includes a vapor reducing section comprising acompressor 60 and condenser 62 by which vapor flowing through the vaporflow circuit is reduced to a liquid for flow to the storage receptacle.The vapor flow circuit further includes a flow line 64 having an inletend 66 connected to system inlet line 46 between sight glass 48 andcheck valve 58. Flow line 64 has an outlet end 68 connected to the inletside of compressor 60 through a normally closed solenoid valve S2, and acheck valve 69 is provided in line 64 adjacent inlet end 66 to precludethe backflow of vapor through inlet line 46. The outlet side ofcompressor 60 is connected to the inlet end of condenser 62 by a flowline 70, and the outlet side of condenser 62 is connected to a flow line72 having an outlet end 74 connected to system outlet line 54. Anormally closed solenoid valve S3 is provided in line 72 between thecondenser and outlet end 74, and the vapor flow circuit further includesa capillary expander 76 having an inlet end 78 connected to flow line 72between condenser 62 and valve S3 and through a strainer 80. The outletend 82 of the capillary expander is connected to flow line 72 betweenvalve S3 and outlet end 74 of the flow line. For the purpose set forthhereinafter, a high pressure switch 84 and a high pressure gage 86, thelatter of which is visible exteriorly of casing 34, are connected toflow line 72 between condenser 62 and valve S3.

Vapor feedback flow circuit 40 includes a flow line 88 having an inletend 90 disposed adjacent the exterior of casing 34 for connection tostorage tank 16 as set forth hereinafter. Flow line 88 has an outlet end92 connected to the inlet side of compressor 60, and a normally closedsolenoid valve S1 and a diaphragm actuated compressor throttling valve94 are provided in flow line 88 between the inlet and outlet endsthereof. A flow line 96 connects the diaphragm chamber of valve 94 withline 70 on the outlet side of compressor 60, whereby the compressoroutlet pressure provides a pilot pressure for operating valve 94. Forthe purpose set forth hereinafter, a low pressure switch 98 and a lowpressure gage 100, the latter of which is visible from the exterior ofcasing 34, are connected to flow line 88 between valve S1 and end 92 ofthe flow line and thus on the inlet side of the compressor, and apressure responsive switch 102 is connected to flow line 88 betweeninlet end 90 thereof and valve 94.

The inlet ends of liquid flow circuit 36 and vapor flow circuit 38 areadapted to be connected to the high pressure liquid and the low pressurevapor sides of refrigeration system 10 by a flexible hose assembly 104which includes a hose 106 having a coupling 108 for attaching the hoseassembly to outer end 50 of inlet line 46. The hose assembly furtherincludes a filter 110 to which hose 106 is connected and a flow divider112 to which a pair of flexible hoses 114 and 116 are connected. Hoses114 and 116 include corresponding couplings 118 by which the hoses areadapted to be connected respectfully to service valves 12 and 14 of therefrigeration system, and each of the hoses is provided with a manuallyoperable in-line shut-off valve 120 to minimize the loss of refrigerantduring attachment and detachment of the recovery apparatus with therefrigeration system. While hose assembly 104 provides a singleconnection to the inlet side of the apparatus and thus the inlet ends ofthe liquid and vapor flow circuits, it will be appreciated that the flowcircuits could have separate inlet ends for connection to separate hosesfor connection to the corresponding one of the high pressure liquid andlow pressure vapor sides of the refrigeration system.

Outlet line 54 of the liquid and vapor flow circuits is adapted to beconnected to liquid line 18 of storage receptacle 16 by means of aflexible hose 122 having couplings 124 at the opposite ends thereof forconnection with outer end 56 of outlet line 54 and liquid valve 22 ofreceptacle 16. Flow line 88 of vapor feedback circuit 40 is adapted tobe connected to vapor line 20 in receptacle 16 by means of a flexiblehose 126 having couplings 128 at the opposite ends thereof forconnection with outer end 90 of flow line 88 and vapor valve 24 ofreceptacle 16. Each of the hoses 122 and 126 is provided with a manuallyoperable in-line shut-off valve 130 for the same purpose as valves 120referred to hereinabove. Preferably, storage receptacle 16 is providedwith a float switch 132 for the purpose set forth hereinafter, and thefloat switch is adapted to be connected to the electric control circuitfor the apparatus through switch cable 134 which extends from housing 34and has a plug 136 at the outer end thereof for connection with a plugreceptacle 138 on storage receptacle 16.

Referring now to FIG. 2 which shows the electric control circuit for therefrigerant recovery apparatus, power lines L1 and L2 of the controlcircuit are adapted to be connected to a 115 volt AC power supply bymeans of a power cord extending from casing 34 and having a plug 140 atthe outer end thereof. Compressor 60 and a cooling fan 142 in paralleltherewith are connected across lines L1 and L2 through a manuallyoperable on-off switch 144 and a normally open relay 146. Coil 148 forrelay 146 is connected across lines L1 and L2 through line 149, normallyclosed low pressure switch 98, a second normally open relay 150, line151, normally closed receptacle float switch 132, normally closed highpressure switch 84, and on-off switch 144. An indicator light 85 isconnected in shunt across high pressure switch 84, and an indicatorlight 133 is connected in shunt across float switch 132, both for thepurpose set forth hereinafter. The control circuit further includes amanually operable selector switch 152 by which the recovery apparatus isselectively operated in the liquid recovery mode and in the vaporrecovery mode. More particularly in this respect, switch 152 is a doublepole double throw switch having switch arms 154 and 156 which, in thesolid line positions thereof shown in FIG. 2, provide for the apparatusto operate in the liquid recovery mode and in the broken line positionsthereof provide for the apparatus to operate in the vapor recovery mode.Switch arm 154 has a base terminal 158 and contacts 160 and 162 betweenwhich the arm is displacable, and switch arm 156 has a base terminal 164and contacts 166 and 168 between which the arm is displacable. Contact160 is connected to line L2 through line 170 and coil 172 of solenoidvalve S1, and contact 162 is connected to line L2 through line 174 andcoils 176 and 178 of solenoid valves S2 and S3, respectfully, which areconnected in parallel with one another between line 174 and line L2.Contact 166 of switch arm 156 is connected to line L2 through line 180and relay coil 148, and contact 168 is connected to line L2 through line182, line 180 and relay coil 148. Line 182 includes an indicator light184 for indicating completion of a refrigerant recovery operation andfunctions in this respect as set forth more fully hereinafter.

Pressure responsive switch 102 associated with flow line 88 of vaporfeedback circuit 40 is interposed between selector switch 152 and lineL1. Switch 102 is a single pole double throw switch having a switch arm186, a base terminal 188 and contacts 190 and 192 between which arm 186is displacable. Switch arm 186 is normally in the solid line positionthereof shown in FIG. 2 and is displaced to the broken line positionthereof in the manner and for the purpose set forth more fullyhereinafter. Base terminal 188 is connected to base terminal 164 ofswitch arm 156 of selector switch 152 by line 194 and is connected toline L1 by line 96, float switch 132, high pressure switch 84 and on-offswitch 144. Contact 190 of switch 102 is connected to base terminal 158of switch arm 154 of selector switch 152 by line 198, and contact 192 ofswitch 102 is connected to line 170 by line 200.

Assuming that the apparatus has been connected to refrigeration system10 and refrigerant recovery storage receptacle 16 as described herein,and further assuming that the apparatus has been purged of air andresidual refrigerant therein by the appropriate manual manipulation ofthe various valves and hose fittings so as to purge high pressure liquidhose 114, low pressure vapor hose 116, liquid flow circuit 36, liquidvalve hose 122, vapor flow circuit 38 and vapor valve hose 126, theapparatus is prepared for a recovery operation which is performed asfollows. It is preferred to first perform a liquid recovery operationand, accordingly, selector switch 152 is positioned to operate therecovery apparatus in the liquid recovery mode, whereby the severalswitches in the apparatus control circuit are in the solid linepositions thereof shown in FIG. 2. Service valve 12 for the highpressure liquid side of refrigeration system 10 is then opened togetherwith valve 120 in high pressure hose 114, liquid and vapor valves 22 and24 of storage receptacle 16 and valves 130 in liquid and vapor hoses 122and 126. The apparatus is then turned on by closing on-off switch 144which connects relay 148 across lines L1 and L2 through normally closedswitches 84 and 132, lines 96 and 94, switch arm 156 of selector switch152 and line 180. Relay coil 148 is thus energized to close relays 146and 150 whereby compressor 60 begins running. Relay 150 connects relaycoil 148 across lines L1 and L2 independent of selector switch 152 forthe purpose set forth hereinafter. Further, the closure of on-off switch144 connects coil 172 of solenoid valve S1 across lines L1 and L2through switches 84 and 132, line 196, switch arm 186 of switch 102,line 198, switch arm 154 of selector switch 152 and line 170, wherebycoil 172 is energized to open solenoid valve S1 and thus connect vapor28 in receptacle 16 in flow communication with the inlet side ofcompressor 60 through vapor feedback circuit 40. In the liquid recoverymode, switch arm 154 of selector switch 152 disengages contact 162,whereby the circuit to coils 176 and 178 of solenoid valves S2 and S3 isopen and valves S2 and S3 are closed.

As will be appreciated from FIG. 1, the foregoing relationships providefor liquid refrigerant from refrigeration system 10 to flow through line42 of liquid flow circuit 36 to storage receptacle 16 through liquidline 18 therein. During such flow, vapor 28 in receptacle 16 is fed backto the inlet side of compressor 60 through feedback circuit 40 and openvalve S1, and this vapor is pumped through compressor 60 and condenser62 and is reduced thereby to a liquid. Since valve S3 is closed, theliquid flows through capillary expander 76 and is cooled thereby andreturned through outlet line 54 to receptacle 16 as a liquid. Duringsuch feedback flow, diaphragm valve 94 throttles the flow of vapor tothe inlet side of compressor 60 based on a pilot pressure in line 70 atthe outlet side of the compressor. High pressure gage 86 on thedownstream side of condenser 62 provides a visual reading of thecompressor discharge pressure during operation of the apparatus in theliquid recovery mode, and high pressure switch 84 operates to shut-downthe apparatus in response to a pre-determined undesirably high pressurewhich opens the switch. Operation of the apparatus in the foregoingmanner continues until all of the liquid refrigerant has been withdrawnfrom refrigeration system 10, and the latter can be determined byobserving the absence of liquid in sight glass 48.

When all of the liquid has been withdrawn, low pressure vapor sideservice valve 14 of refrigeration system 10 is opened as is valve 120 inlow pressure vapor hose 116, and selector switch 152 is displaced to thevapor recovery mode position thereof, whereby switch arms 154 and 156move to the broken line positions thereof shown in FIG. 2. Thus, as willbe appreciated from FIG. 2, switch arm 154 disengages contact 160 toopen the circuit to coil 172 of solenoid valve S1, whereby the lattervalve closes, and the switch arm engages contact 162 to connect solenoidcoils 176 and 178 across lines L1 and L2, whereby the coils areenergized to open solenoid valves S2 and S3. At the same time, switcharm 156 disengages contact 166 and engages contact 168. While this opensthe circuit to line 180, relay coil 148 remains energized acrossnormally closed low pressure switch 98 and previously closed relay 150,whereby relay 146 remains closed and compressor 60 continues to run. Theengagement of switch arm 156 with contact 168 connects indicator light184 in shunt across low pressure switch 98 and relay 150, whereby theindicator light is unlit at the beginning of the vapor recoveryoperation. During the vapor recovery operation, vapor from the lowpressure side of refrigeration system 10 flows through vapor flowcircuit 38 and thus through solenoid valve S2 to compressor 60 andcondenser 62. The vapor is thus reduced to a liquid which flows throughopen solenoid valve S3 and thence through line 72 to outlet line 54 andto storage tank 16 through liquid line 18 thereof. During operation inthe vapor recovery mode in the foregoing manner, solenoid valve S1 isclosed, whereby there is no feedback of vapor 28 from receptacle 16through feedback circuit 40.

The liquid flowing from condenser 62 follows the path of leastresistance through solenoid valve S3 and thus bypasses capillaryexpander 76 and the cooling effect achieved with respect to flow of theliquid therethrough to receptacle 16 during liquid recovery.Accordingly, during vapor recovery operation, the temperature inreceptacle 16 and thus the pressure therein can become undesirably high.While the recovery apparatus could be shut down under such circumstancesuntil the temperature drops to an acceptable level, it is preferred tomonitor the pressure in receptacle 16, and thus the temperature, and toshift the apparatus back to the liquid recovery mode. This shift reopensvapor feedback circuit 40 for the flow of vapor from receptacle 16 tothe inlet side of compressor 60 and thence to condenser 62, whereby thevapor is reduced to a liquid and returned to receptacle 16 throughcapillary expander 76. Such shifting of the apparatus is achieved bypressure responsive switch 102 in vapor feedback circuit 40. Moreparticularly in this respect, and as will be appreciated from FIG. 2,when the pressure in receptacle 16 and thus the temperature thereinreaches a predetermined undesirably high level switch arm 186 ofpressure responsive switch 102 is displaced from the solid line positionthereof to the broken line position, thus to disengage contact 190 andto engage contact 192. In the vapor recovery phase, switch arm 154 ofselector switch 152 is in the broken line position thereof shown in FIG.2, whereby displacement of switch arm 186 of switch 102 to its brokenline position opens the circuit through line 198 to coils 176 and 178 ofsolenoid valves S2 and S3, whereby the latter close. At the same time,engagement of switch arm 186 with contact 192 of switch 102 closes thecircuit through lines 200 and 170 to coil 172 of solenoid valve S1,whereby the latter opens. Thus, vapor in receptacle 16 is fed backthrough flow circuit 40 as described above until such time as thepressure in receptacle 16 drops to an acceptable level. When the latteroccurs the apparatus shifts back to the vapor recovery mode by thereturn of switch arm 186 to the solid line position thereof in FIG. 2.This shift causes solenoid valve S1 to close and solenoid valves S2 andS3 to reopen, whereby the apparatus functions to reduce vapor from thelow pressure vapor side of refrigeration system 10 as described above.The foregoing shifting of the apparatus from the vapor recovery mode tothe liquid recovery mode and back to the vapor recovery mode withselector switch 152 in the vapor recovery mode position thereofcontinues until such time as all of the vapor in the low pressure sideof the refrigeration system as been recovered. Such automatic cycling ofthe apparatus advantageously minimizes the overall recovery time. Whenthe recovery of vapor has been completed, the apparatus automaticallyshuts down. In this respect, normally closed low pressure switch 98opens in response to a predetermined vacuum pressure when all of thevapor has been recovered to open the circuit to relay coil 148 thus toopen the circuit to compressor 60 by opening relay 146. Low pressuregage 100 provides a visual indication of the pressure during the vaporrecovery procedure. The opening of low pressure switch 98 energizesindicator light 184 to provide a visual indication that recovery iscomplete. High pressure switch 84 is responsive to a higher pressurethan that of switch 102 and is operable in response to an undesirablyhigh compressor discharge pressure or receptacle pressure duringoperation of the apparatus to open the circuit to relay coil 148, thusto shut down the compressor. The opening of high pressure switch 84energizes indicator light 85 for visually indicating the existence of ahigh pressure condition. If the level of liquid 26 in receptacle 16reaches that of float switch 132, the latter likewise opens the circuitto relay coil 148 to shut down compressor 60, and the opening of switch132 energizes indicator light 133 to visually indicate that thereceptacle is full.

When operating the recovery apparatus in the liquid recovery mode, andwhen shifting to the liquid recovery mode in response to a high pressurein the storage receptacle, air in the liquid on the downstream side ofcondenser 62 cannot easily pass through capillary expander 76 and, thus,backs up in the condenser. This results in a low cooling capacity and ahigh operating pressure which can actuate high pressure switch 84causing the apparatus to cycle on and off. Such cycling precludescontinuous operation of the apparatus and increases the operating timerequired to complete a recovery operation. This disadvantage is overcomein accordance with the present invention by incorporating a gas purgingarrangement 202 in the apparatus on the downstream side of condenser 62,as shown in FIG. 3, and incorporating a purging control circuit 204 inthe apparatus control circuit as shown in FIG. 4 of the drawing.Otherwise, the component parts of the apparatus and control circuit arestructurally and functionally the same as that described hereinabove inconjunction with FIGS. 1 and 2 of the drawing and, accordingly, aredesignated in FIGS. 3 and 4 by the same numbers and letters.

Referring first to FIG. 3, purging arrangement 202 is interposed in flowline 72 between the downstream side of condenser 62, solenoid valve S3and capillary expander 76. In the embodiment illustrated, purgingarrangement 202 includes a horizontal gas separating chamber 206 havingan inlet end 208 defined by line 72 and having an outlet end defined byline 210 connected to strainer 80 of capillary expander 76. The top ofchamber 206 adjacent outlet end 210 thereof is connected by line 212 inflow communication with solenoid valve S3 and line 72. Purgingarrangement 202 further includes a vertically disposed float and gasaccumulating chamber 214 having a necked in lower end 216 opening intothe top of chamber 206 at a location closer to outlet end 210 than toinlet end 208. Chamber 214 houses a float 218 which is operable as setforth more fully hereinafter to control a float switch 220 which has anormally open or deactivated position and which, when closed oractivated, enables opening of a normally closed solenoid valve S4 toexhaust accumulated gas to atmosphere. More particularly in thisrespect, chamber 214 has an upper end 222 in which gas removed from theliquid refrigerant accumulates as set forth hereinafter. Upper end 222is provided with an outlet line 224 normally closed by solenoid valve S4and for the purpose set forth hereinafter, the exhaust of accumulatedgas through valve S4 to atmosphere is preferably through a capillarytube 226. Float 218 is reciprocable in chamber 214 between upper andlower stops 228 and 230, respectively, and in the embodiment illustratedthe lower stops are defined by a pair of electrical contacts adapted tobe bridged by float 218, or conductive material attached thereto, toachieve closing of switch 220 when float 218 is in its lower mostposition. Stops 228 and contacts 230 are mounted on a tubular floatguide 232 extending downwardly in chamber 214 from switch 220 and whichfloat guide encloses the electrical switch wires, not shown, for switchcontacts 230.

In the embodiment illustrated, compressor 62 is a 1/3 horse powerreciprocating compressor operating between design pressures of fromabout 215 PSI to about 395 PSI, and separating chamber 206 isconstructed from copper tubing and is about 7 inches long and has anouter diameter of about 0.75 inch. Inlet end 208, outlet end 210 andline 212 are defined by copper tubing brazed to chamber 206 and havingan inner diameter of about 0.2 inch. Capillary expander 76 is a coppertube having an uncoiled length of about 4 feet and an inner diameter ofabout 0.036 inch. Float and gas storage chamber 214 has a height ofabout 8 inches and is defined by copper tubing having an inner diameterof about 1 inch above lower end 216 which has a diameter of about 0.5inch and is brazed to chamber 206. Capillary tube 226 has an uncoiledlength of about 10 feet and an inner diameter of about 0.028 inch andserves to control the time and flow rate of the venting of purged gas toatmosphere.

Referring now to FIG. 4, purge control circuit 204 includes float switch220, a solenoid coil 234 for solenoid valve S4, and a timer 236 whichhas a timing cycle including purge and non-purge portions for thepurpose set forth hereinafter. Timer 236, float switch 220 and solenoidcoil 234 are connected in series with one another and in parallel withcoil 172 of solenoid valve S1 between lines 170 and L2 Accordingly, aswill be appreciated from the foregoing description of apparatus controlcircuit 32, control circuit 204 is adapted to be activated when selectorswitch 152 is positioned for the apparatus to operate in the liquidrecovery mode. Likewise, when the selector switch is positioned for theapparatus to operate in the vapor recovery mode control circuit 204 isadapted to be activated in conjunction with shifting back to the liquidrecovery mode in response to a high pressure in storage receptacle 16.Timer 236 is connected between lines 170 and L2 by lines 238 and 240which provide for the timing cycle of timer 36 to be initiated uponactivation of the purge control circuit in the liquid recovery mode andin response to the shifting to the latter mode during a vapor recoveryoperation. During the purge portion of the time cycle of timer 236, thetimer completes a circuit between lines 238 and line 242 to float switch220, and during the non-purge portion of the time cycle, the lattercircuit is open. Accordingly, as will become more apparent hereinafter,the purge and non-purge portions of the timer cycle respectively enableand disable the exhausting of accumulated gas to atmosphere from upperend 222 of chamber 214.

It is believed that the following description of the operation of thepurging arrangement will be understood from the foregoing description ofthe purging apparatus and purging control circuit together with theforegoing description of the recovery apparatus and apparatus controlcircuit illustrated in FIGS. 1 and 2. When selector switch 152 ispositioned for the apparatus to operate in the liquid recovery mode,solenoid valve S1 is open, solenoid valves S2 and S3 are closed, andliquid refrigerant from the high pressure side of refrigeration system10 flows through liquid flow circuit 36 to refrigerant storagereceptacle 16 as described hereinabove. Further, vapor 28 in the liquidstorage receptacle is fed back through flow circuit 40 to the inlet sideof compressor 60 and thence to condenser 62 whereby the vapor is reducedto a liquid. The liquid from condenser 62 flows into inlet end 208 ofseparation chamber 206 of purging arrangement 202, and the relativedimensions of inlet 208 and chamber 206 provide for the velocity of theliquid refrigerant LR entering the chamber to decrease and for gas A inthe liquid refrigerant to gravitate to the top of chamber 206 and tomove therealong and into float and storage chamber 214 through entranceend 216 thereof. Liquid refrigerant also enters the float and storagechamber, and gas entering the latter chamber gravitates therethrough andaccumulates in upper end 222 of the chamber. Liquid refrigerant with thegas thus removed flows through outlet end 210 of chamber 206 and thencethrough capillary expander 76 to the liquid inlet 18 line of receptacle16.

As gas accumulates in upper end 222 of chamber 214, float 118 movesdownwardly form its upward most position as defined by stop 228. When apre-determined quantity of gas has accumulated in upper end 222 ofchamber 214, float 218 engages contacts 230 to activate or close floatswitch 220. In the preferred embodiment, float 218 is of hollow,stainless steel construction and thus provides for bridging contacts 230to close the switch. As mentioned above, timer 236 has a timing cyclewhich is initiated when selector switch 152 is moved to the position tooperate the apparatus in the liquid recovery mode. If, upon the closureof float switch 220, timer 236 is in the purge mode, solenoid coil 234is energized to open solenoid valve S4. If timer 236 is in the non-purgeportion of the timer cycle, solenoid coil 234 remains de-energized untilsuch time as the timer moves into the purge portion of the cycle. Thetiming cycle of timer 236 continuously repeats whereby, so long asselector switch 152 remains in the liquid recovery mode position, gas isexhausted to atmosphere from upper end 222 of chamber 214 when floatswitch 220 is closed and timer 236 is in the purge portion of the timercycle. The non-purge portion of the time cycle provides a timing periodduring each timer cycle for gas to accumulate in upper end 222 ofchamber 214, and the purge portion provides a short period forexhausting the gas. Preferably, the cycle time is 30 seconds and thepurge portion of the cycle is a short time such as, for example, thelast 5 seconds of each 30 seconds that the timer is activated. It willbe appreciated that the exhausting of gas to atmosphere requires boththe closure of float switch 220 and operation of timer 236 in thepurging portion of the time cycle. It will be further appreciated thatpurge control circuit 204 is enabled by positioning selector switch 152for operating the apparatus in the liquid recovery mode, and that theopening of valve S4 and thus the exhausting of gas to atmosphere isenabled thereafter by both float switch 220 and timer 236. In thisrespect, the valve is actuated to its open position only when the floatswitch is closed and the timer is in the purge portion of the timecycle.

As will be appreciated from the description thus far of the operation ofpurging arrangement 202, it is not necessary to pre-purge therefrigerant recovery system by manually manipulating the several valvesand hose fittings as heretofore required. In this respect, any gas inthe hoses or recovery apparatus will flow through liquid flow circuit 36to the storage receptacle 16 and separate from the liquid refrigeranttherein for flow through vapor feedback circuit 40 and thence to chamber206 for separation from the liquid refrigerant, accumulation andexhausting to atmosphere as described hereinabove. Such purging inconnection with initial start up of the recovery process advantageouslyreduces the overall recovery time.

When the liquid recovery operation is completed as indicated byobserving sight glass 48, the operator manually actuates the selectorswitch 152 to the position thereof for the apparatus to operate in thevapor recovery mode, whereupon solenoid valve S1 closes and solenoidvalves S2 and S3 open. The apparatus then operates as describedhereinabove in conjunction with FIGS. 1 and 2 to flow vapor from the lowpressure vapor side of refrigeration system 10 through vapor flowcircuit 38, whereby the vapor is reduced to a liquid which flows throughseparation chamber 206 of purging arrangement 202 and thence throughline 212 and solenoid valve S3 to liquid inlet line 18 of receptacle 16.More particularly in this respect, with valve S3 open the liquid flowingthrough chamber 202 is shunted to bypass capillary expander 76. Duringvapor recovery operation, switch arm 154 of selector switch 152 opensthe circuit to purge control circuit 204, whereby the purgingarrangement is disabled with respect to exhausting accumulated gas toatmosphere from upper end 222 of chamber 214. At the same time, however,gas in the liquid refrigerant flowing through separation chamber 206will gravitate therefrom into chamber 214 and into upper end 222thereof. When the temperature and thus the pressure in receptacle 16reaches an undesirably high level, pressure responsive switch 102automatically shifts the apparatus back to the liquid recovery mode asdescribed hereinabove in conjunction with FIGS. 1 and 2. As will beappreciated from FIG. 4, such shifting of the apparatus control byswitch 102 functions to close the circuit to purge control circuit 204thus to actuate timer 236 and enable the exhausting of accumulated gasin upper end 222 of chamber 214 to atmosphere. If the accumulation ofgas in upper end 222 of chamber 214 is sufficient at this time to closefloat switch 220, solenoid valve S4 will open during the purge portionof the time cycle of timer 236 to exhaust air to atmosphere for thepurging time portion of the timer cycle. As described in conjunctionwith FIGS. 1 and 2, the shifting function resulting from the operationof pressure responsive switch 102 opens solenoid valve S1 and thusconnects vapor feedback circuit 40 from receptacle 16 with the inletside of compressor 60 and closes solenoid valves S2 and S3. Accordingly,vapor 28 in receptacle 16 is fed back to the compressor and condenserfor reduction to a liquid from which gas is removed by purgingarrangement 202 as described above. Again, as will be appreciated fromthe previous description with regard to the embodiment disclosed, thecycle of timer 236 will be activated each 30 seconds that the apparatusremains in the liquid recovery mode, enabling gas accumulated in upperend 222 of chamber 214 to be exhausted to atmosphere for 5 secondsduring each 30 second cycle.

When the temperature and thus the pressure in storage receptacle 16drops to an acceptable level, pressure responsive switch 102 shifts thecontrol circuit back to the vapor recovery mode established by selectorswitch 152, whereby solenoid valve S1 closes, solenoid valves S2 and S3open and the circuit to purge control circuit 204 is opened. Theapparatus then recommences operating in the vapor recovery mode asdescribed above. When vapor recovery is completed as describedhereinabove with regard to FIGS. 1 and 2, low pressure switch 98 opensto shut down the apparatus.

While it is preferred to operate the refrigerant recovery apparatusautomatically both with respect to the exhausting of accumulated gas toatmosphere from the purging arrangement and with respect to shifting theapparatus into the liquid recovery mode during a vapor recoveryoperation in response to the pressure in storage receptacle 16, it willbe appreciated that the apparatus can be modified for these functions tobe achieved manually. In this respect, for example, the purgingarrangement can be provided with an indicator such as a light tovisually indicate a pre-determined accumulation of gas in upper end 222of chamber 214, and a push button valve can be provided in place ofsolenoid valve S4 for manual operation by the operator to exhaust gas toatmosphere until such time as the indicator light is extinguished.Further with regard to such manual operation, a temperature gage or apressure gage could replace pressure responsive switch 102 to provide anoperator with a visual indication of the temperature or pressure instorage receptacle 16. Upon observing an undesirably high pressure ortemperature, the operator could manually displace selector switch 152back to the position thereof in which the apparatus operates in theliquid recovery mode. Upon the pressure or temperature dropping to anacceptable level, the operator would then displace switch 152 back tothe position for operating the apparatus in the vapor recovery mode.

Moreover, while considerable emphasis has been placed on the componentparts of the purging arrangement illustrated and described herein, itwill be appreciated that many modifications can be made with respect tothe preferred embodiment without departing from the principals of theinvention. In this respect, for example, level sensing devices otherthan the float arrangement disclosed can be employed for sensing theliquid level in gas accumulating chamber 214 and thus the quantity ofgas accumulated therein. Alternatively, a pressure sensing arrangementcould be employed in conjunction with upper end 222 of the accumulatingchamber to provide for exhausting accumulated gas to atmosphere based ondetecting a pre-determined pressure. Further, the exhaust valve S4 couldbe provided with a small valve port or orifice in place of capillarytube 226 for the purpose of controlling the flow rate of exhausted gasto atmosphere. Still further, while it is preferred to time theexhausting of accumulated gas to atmosphere as described herein, it willbe appreciated that the exhausting of gas to atmosphere could beachieved under the control of the float switch or a similar deviceresponsive to a pre-determined accumulation of gas in storage chamber214. These and other modifications of the preferred embodiment as wellas other embodiments of the invention will be obvious and suggested tothose skilled in the art, whereby it is to be distinctly understood thatthe foregoing descriptive matter is to be interpreted merely asillustrative of the present invention and not as a limitation.

Having thus described the invention, it is claimed:
 1. Apparatus forrecovering refrigerant from a refrigeration system having a highpressure liquid side and a low pressure vapor side, said apparatuscomprising receptacle means for receiving recovered refrigerant andhaving liquid inlet and vapor outlet means opening thereinto, meansincluding vapor reducing means for flowing vapor from said low pressureside to said receptacle means as a liquid, means for flowing liquidrefrigerant from said high pressure side to said receptacle means, meansincluding control means for connecting said vapor outlet means with saidvapor reducing means during said flowing of said liquid refrigerant fromsaid high pressure side and for disconnecting said vapor outlet meansfrom said vapor reducing means during said flowing of vapor from saidlow pressure side, purging means between said vapor reducing means andsaid liquid inlet means for removing gas from liquid refrigerant flowingto said receptacle means, and purging control means including means forenabling said purging means during said flowing of liquid refrigerantfrom said high pressure side and for disabling said purging means duringsaid flowing of vapor from said low pressure side.
 2. Apparatusaccording to claim 1, wherein means for connecting said vapor outletmeans with said vapor said control means includes means responsive to acondition in said receptacle means during said flowing of said vaporfrom said low pressure side for disconnecting flow of vapor from saidlow pressure side to said reducing means and connecting said vaporoutlet means with said vapor reducing means.
 3. Apparatus according toclaim 1, wherein said purging means includes accumulating means foraccumulating gas removed from said liquid, and means including meansresponsive to a given accumulation of gas for releasing gas toatmosphere from said accumulating means.
 4. Apparatus according to claim1, wherein said purging means includes means for accumulating gasremoved from said liquid, sensing means for sensing the amount of gasaccumulated, and means including means responsive to said sensing meansfor releasing gas to atmosphere from said accumulating means. 5.Apparatus according to claim 1, wherein said purging means includesmeans for releasing gas removed from said liquid to atmosphere, and saidpurging control means includes means for enabling said means forreleasing gas during said flowing of liquid refrigerant from said highpressure side and for disabling said means for releasing gas during saidflowing of vapor from said low pressure side.
 6. Apparatus forrecovering refrigerant from a refrigeration system having a highpressure liquid side and a low pressure vapor side, said apparatuscomprising receptacle means for receiving recovered refrigerant andhaving liquid inlet and vapor outlet means opening thereinto, meansincluding vapor reducing means for flowing vapor from said low pressureside to said receptacle means as a liquid, means for flowing liquidrefrigerant from said high pressure side to said receptacle means, meansincluding control means for connecting said vapor outlet means with saidvapor reducing means during said flowing of said liquid refrigerant fromsaid high pressure side and for disconnecting said vapor outlet meansfrom said vapor reducing means during said flowing of vapor from saidlow pressure side, and purging means between said vapor reducing meansand said liquid inlet means for removing gas from liquid refrigerantflowing to said receptacle means, said purging means including means forreleasing gas removed from said liquid to atmosphere, and means operableduring said flow of liquid refrigerant for periodically enabling saidmeans for releasing gas.
 7. Apparatus according to claim 6, wherein saidmeans for periodically enabling said means for releasing gas includestimer means having a purge mode and a non-purge mode.
 8. Apparatusaccording to claim 7, wherein said purging means includes accumulatingmeans for accumulating gas removed from said liquid, and said means forperiodically enabling said means for releasing gas further includesmeans responsive to a given accumulation of gas in said accumulatingmeans to activate said means for releasing gas when said timer means isin said purge mode.
 9. Apparatus according to claim 8, wherein saidmeans responsive to a given accumulation of gas includes switch meanshaving activated and deactivated positions and said means for releasinggas includes valve means having open and closed positions, said switchmeans being in said activated position in response to said givenaccumulation, and said valve means being in said open position when saidswitch means is in said activated position and said timer means is insaid purge mode.
 10. Apparatus according to claim 9, wherein said timermeans has a time cycle of predetermined duration, a first portion ofsaid cycle providing said purge mode of said timer means and a secondportion of said cycle providing said non-purge mode.
 11. Apparatusaccording to claim 10, wherein said second portion of said time cycle isof longer duration than said first portion.
 12. Apparatus according toclaim 1, wherein said purging means includes first chamber means forreceiving liquid flowing from said vapor reducing means, second chambermeans above and communicating with said first chamber means for gas insaid liquid to gravitate into said second chamber means, said secondchamber means receiving liquid from said first chamber means and havingan upper end in which said gas accumulates above liquid receivedtherein, and means for releasing said gas from said upper end toatmosphere.
 13. Apparatus according to claim 12, wherein said means forreleasing gas includes normally closed valve means.
 14. Apparatusaccording to claim 13, wherein said and purging control means includesmeans for controlling the opening of said valve means for releasing saidgas to atmosphere.
 15. Apparatus according to claim 14, wherein saidpurging control means includes sensing means for sensing the quantity ofgas accumulated in said upper end of said second chamber means, andmeans including means responsive to said sensing means for enabling anddisabling opening of said valve means.
 16. Apparatus according to claim15, wherein said means responsive to said sensing means includes switchmeans having activated and deactivated positions, said switch means insaid activated position enabling opening of said valve means and in saiddeactivated position disabling opening of said valve means. 17.Apparatus according to claim 16, wherein said means for enabling anddisabling opening of said valve means further includes timer meanshaving a timing cycle including a purge portion and a non-purge portion,said timer means in said purge portion of said cycle enabling opening ofsaid valve means and in said non-purge portion disabling opening of saidvalve means.
 18. Apparatus according to claim 17, wherein said sensingmeans includes level sensing means for sensing the level of said liquidreceived in said second chamber means.
 19. Apparatus according to claim18, wherein said level sensing means includes float means.
 20. Apparatusfor recovering refrigerant from a refrigeration system having a highpressure liquid side and a low pressure vapor side, said apparatuscomprising receptacle means for receiving recovered refrigerant andhaving liquid inlet and vapor outlet means opening thereunto, meansincluding vapor reducing means for flowing vapor from said low pressureside to said receptacle means as a liquid, means for flowing liquidrefrigerant from said high pressure side to said receptacle means, meansincluding control means for connecting said vapor outlet means with saidvapor reducing means during said flowing of said liquid refrigerant fromsaid high pressure side and for disconnecting said vapor outlet meansfrom said vapor reducing means during said flowing of vapor from saidlow pressure side, said control means including means responsive to acondition in said receptacle means during said flowing of vapor fromsaid low pressure side for disconnecting flow of vapor to said reducingmeans from said low pressure side and for connecting said vapor outletmeans with said vapor reducing means, purging means between said vaporreducing means and said liquid inlet means for removing gas from liquidrefrigerant flowing to said receptacle means, said purging meansincluding means for releasing gas removed from said liquid toatmosphere, and purge control means including means for enabling saidmeans for releasing gas to atmosphere during said flowing of liquidrefrigerant from said high pressure side and for disabling said meansfor releasing gas to atmosphere during said flowing of vapor from saidlow pressure side.
 21. Apparatus according to claim 20, wherein saidpurge control means has enabled and disabled conditions, said purgecontrol means being in said enabled condition during said flowing ofliquid refrigerant from said high pressure side and being in saiddisabled condition during said flowing of vapor from said low pressureside, and said means responsive to a condition in said receptacle meansincluding switch means for shifting said purge control means from saiddisabled to said enabled condition during said flowing of vapor fromsaid low pressure side.
 22. Apparatus according to claim 21, whereinsaid means for releasing gas to atmosphere includes normally closedelectrically actuated valve means, and said purge control means includesenabling means for enabling the opening of said valve means. 23.Apparatus according to claim 22, wherein said enabling means includestimer means having activated and deactivated modes, said timer meansbeing in said activated mode when said switch means shifts said purgecontrol means from said disabled to said enabled condition. 24.Apparatus according to claim 23, wherein said timer means in saidactivated mode has a timing cycle including first and second cycleportions, said timing means in said first and second cycle portionsrespectively enabling and disabling opening of said valve means. 25.Apparatus according to claim 22, wherein said purging means includesmeans for accumulating said gas removed from liquid refrigerant and saidenabling means includes means responsive to a predetermined accumulationof gas for enabling opening of said valve means.
 26. Apparatus accordingto claim 25, wherein said switch means is first switch means and saidmeans responsive to a predetermined accumulation of gas includes secondswitch means having activated and deactivated conditions respectivelyenabling and disabling opening of said valve means.
 27. Apparatusaccording to claim 26, wherein said purging means includes sensing meansfor sensing said accumulation of gas, said second switch means being insaid activated condition in response to said sensing means sensing saidpredetermined accumulation of gas.
 28. Apparatus according to claim 27,wherein said enabling means further includes timer means havingactivated and deactivated modes, said timer means being in saidactivated mode when said first switch means shifts said purge controlmeans from said disabled to said enabled condition.
 29. Apparatusaccording to claim 28, wherein said timer means in said activated modehas a timing cycle including first and second cycle portions, saidtiming means in said first and second cycle portions respectivelyenabling and disabling opening of said valve means.
 30. Apparatusaccording to claim 20, wherein said purging means includes first chambermeans for receiving liquid flowing from said vapor reducing means,second chamber means above and communicating with said first chambermeans for gas in said liquid to gravitate into said second chambermeans, said second chamber means receiving liquid from said firstchamber means and having an upper end in which said gas accumulatesabove liquid received therein, and said means for releasing gas being atsaid upper end.
 31. Apparatus according to claim 30, wherein said firstchamber means is a horizontally disposed first tubular chamber havingspaced apart inlet and outlet passageway means connected respectively tosaid vapor reducing means and said liquid inlet means of said receptaclemeans, said second chamber means being a vertically disposed secondtubular chamber having a lower end opening into said first chamberbetween said inlet and outlet passageway means thereof, and said meansfor releasing gas including outlet means in said upper end of saidsecond chamber.
 32. Apparatus according to claim 31, and capillary tubemeans connecting said outlet passageway means of said first chamber withsaid liquid inlet means of said receptacle means.
 33. Apparatusaccording to claim 31, wherein said means for releasing gas includesmeans connected to said outlet means for controlling the flow rate ofsaid gas to atmosphere.
 34. Apparatus according to claim 31, whereinsaid lower end of said second chamber opens into said first chambercloser to said outlet passageway means than to said inlet passagewaymeans.
 35. Apparatus according to claim 31, and shunt flow line meansbetween said first chamber and said liquid inlet means of saidreceptacle means for liquid from said vapor reducing means to bypasssaid outlet passageway means during said flowing of vapor from said lowpressure side.
 36. Apparatus according to claim 31, wherein said meansfor releasing gas includes valve means connected to said outlet means,said valve means having open and closed positions respectively enablingand blocking the flow of gas from said upper end of said second chamberto atmosphere, and said purge control means including means for enablingopening said valve means in response to a predetermined accumulation ofgas in said upper end.
 37. Apparatus according to claim 36, wherein saidvalve means is electrically activated and said means for enablingopening said valve means includes sensing means for sensing saidpredetermined accumulation of gas and means including switch meansresponsive to said sensing means for enabling activation of said valvemeans when said sensing means senses said predetermined accumulation.38. Apparatus according to claim 37, wherein said sensing means includesfloat means in said second chamber and said switch means includes spacedapart contacts in said second chamber, said float means having a sensingposition corresponding to said predetermined accumulation, and saidfloat means including electrically conductive means for bridging saidcontacts in said sensing position.
 39. Apparatus according to claim 36,wherein said lower end of said second chamber opens into said firstchamber closer to said outlet passageway means than to said inletpassageway means.
 40. Apparatus according to claim 39, wherein saidvalve means has upstream and downstream sides with respect to the flowof gas therethrough from said second chamber, and means on thedownstream side of said valve means for controlling the flow rate ofsaid gas to atmosphere.
 41. Apparatus according to claim 40, whereinsaid valve means is electrically activated and said means for enablingopening said valve means includes sensing means for sensing saidpredetermined accumulation of gas and means including switch meansresponsive to said sensing means for enabling activation of said valvemeans when said sensing means senses said predetermined accumulation.42. Apparatus according to claim 41, wherein said sensing means includesfloat means in said second chamber and said switch means responsive tosaid sensing means includes spaced apart contacts in said secondchamber, said float means having a sensing position corresponding tosaid predetermined accumulation, and said float means includingelectrically conductive means for bridging said contacts in said sensingposition.
 43. Apparatus according to claim 42, wherein said means onsaid downstream side of said valve means includes capillary tube means.44. Apparatus according to claim 40, and shunt flow line means betweensaid first chamber and said liquid inlet means of said receptacle meansfor liquid from said vapor reducing means to bypass said outletpassageway means during said flowing of vapor from said low pressureside.
 45. Apparatus according to claim 40, wherein said means forcontrolling the flow rate of gas to atmosphere includes capillary tubemeans.
 46. Apparatus for recovering refrigerant from a refrigerationsystem having a high pressure liquid side and a low pressure vapor side,said apparatus comprising receptacle means for receiving refrigerantrecovered from said system, said receptacle means including liquidpassageway means and vapor passageway means opening thereunto, liquidflow circuit means having inlet end means for connection to said highpressure liquid side of said system, vapor flow circuit means havinginlet end means for connection to said low pressure vapor side of saidsystem, said liquid flow circuit means including outlet end means forconnecting said liquid flow circuit means with said liquid passagewaymeans of said receptacle means, said vapor flow circuit means includingoutlet end means for connecting said vapor flow circuit means with saidliquid passageway means of said receptacle means, compressor means andcondenser means in said vapor flow circuit means between said inlet endmeans and outlet end means thereof for reducing vapor to liquid, saidcompressor means having an inlet side, vapor flow line means betweensaid vapor passageway means of said receptacle means and said inlet sideof said compressor means, apparatus control means including means foroperating said apparatus in a liquid recovery mode and a vapor recoverymode, said apparatus control means in said liquid recovery modeincluding means for connecting said inlet side of said compressor meansin flow communication with said receptacle means through said vapor flowline means, purging means between said condenser means and said outletend means of said vapor flow circuit means for removing gas from liquidflowing from said condenser means to said outlet end means of said vaporflow circuit means during said liquid recovery mode, said purging meansincluding means for accumulating gas removed from said liquid, normallyclosed electrically activated purging valve means for releasingaccumulated gas to atmosphere, and purging control circuit means forcontrolling opening of said valve means, said apparatus control meansincluding means to activate said purging control circuit means in saidliquid recovery mode and to deactivate said circuit in said vaporrecovery mode.
 47. Apparatus according to claim 46, wherein said purgingcontrol circuit means includes sensing means for sensing accumulatedgas, and means including switch means responsive to said sensing meansfor enabling opening of said valve means when said sensing means sensesa predetermined accumulation of gas.
 48. Apparatus according to claim47, wherein said means for enabling opening of said valve means furtherincludes timer means having activated and deactivated modes respectivelycorresponding to activation and deactivation of said purging controlcircuit means.
 49. Apparatus according to claim 48, wherein said timermeans in said activated mode includes a time cycle having purge andnon-purge time portions during which opening of said purging valve meansis respectively enabled and disabled.
 50. Apparatus according to claim48, wherein said apparatus control means in said vapor recovery modeincludes means for disconnecting said inlet side of said compressormeans from flow communication with said receptacle means through saidvapor flow line means, and means responsive to a predetermined pressurein said receptacle means during said vapor recovery mode for shiftingsaid apparatus from said vapor recovery mode to said liquid recoverymode and for activating said purging control circuit means. 51.Apparatus according to claim 48, wherein said purging means includesfirst chamber means for receiving liquid flowing from said condensermeans, second chamber means above and communicating with said firstchamber means for gas in said liquid to gravitate into said secondchamber means, said second chamber means receiving liquid from saidfirst chamber means and having an upper end providing said means foraccumulating gas removed from said liquid, said upper end includingoutlet means, and said purging valve means being connected to saidoutlet means.
 52. Apparatus according to claim 51, wherein said firstchamber means is a horizontally disposed first tubular chamber havingspaced apart inlet and outlet passageway means connected respectively tosaid condenser means and said outlet end means of said vapor flowcircuit means, and said second chamber means being a vertically disposedsecond tubular chamber having a lower end opening into said firstchamber between said inlet and outlet passageway means thereof. 53.Apparatus according to claim 52, and capillary tube means connectingsaid outlet passageway means of said first chamber with said outlet endmeans of said vapor flow circuit means.
 54. Apparatus according to claim52, and capillary tube means connected to said purging valve means forcontrolling the flow rate of said gas to atmosphere.
 55. Apparatusaccording to claim 52, wherein said lower end of said second chamberopens into said first chamber closer to said outlet passageway meansthan to said inlet passageway means.
 56. Apparatus according to claim52, and shunt flow line means between said first chamber and said outletend means of said vapor flow circuit means for liquid from saidcondenser to bypass said outlet passageway means when said apparatus isin said vapor recovery mode.
 57. Apparatus according to claim 46,wherein said apparatus control means in said vapor recovery modeincludes means for disconnecting said inlet side of said compressormeans from flow communication with said receptacle means through saidvapor flow line means, and means responsive to a predetermined pressurein said receptacle means during said vapor recovery mode for shiftingsaid apparatus from said vapor recovery mode to said liquid recoverymode and for activating said purging control circuit means. 58.Apparatus according to claim 57, further including capillary tube meansconnecting said outlet passageway means of said first chamber with saidoutlet end means of said vapor flow circuit means, and shunt flow linemeans between said first chamber and said outlet end means of said vaporflow circuit means for liquid from said condenser means to bypass saidoutlet passageway means when said apparatus is in said vapor recoverymode.
 59. Apparatus according to claim 57, wherein said means forenabling opening of said valve means further includes timer means havingactivated and deactivate modes respectively corresponding to activationand deactivation of said purging control circuit means, said timer meansin said activated mode having a time cycle including purge and non-purgeportions during which opening of said purging valve means isrespectively enabled and disabled.
 60. Apparatus according to claim 59,wherein said purging means includes a horizontally disposed firsttubular chamber having spaced apart inlet and outlet passageway meansconnected respectively to said condenser means and said outlet end meansof said vapor flow circuit means, and a vertically disposed secondtubular chamber having a lower end opening into said first chamberbetween said inlet and outlet passageway means thereof.
 61. Apparatusaccording to claim 60 wherein, said lower end of said second chamberopens into said first chamber closer to said outlet passageway meansthan to said inlet passageway means.
 62. Apparatus according to claim61, and capillary tube means connected to said purging valve means forcontrolling the flow rate of said gas to atmosphere.
 63. Apparatusaccording to claim 62, further including capillary tube means connectingsaid outlet passageway means of said first chamber with said outlet endmeans of said vapor flow circuit means, and shunt flow line meansbetween said first chamber and said outlet end means of said vapor flowcircuit means for liquid from said condenser means to bypass said outletpassageway means when said apparatus is in said vapor recovery mode. 64.A method of recovering refrigerant from a refrigeration system having ahigh pressure liquid side and a low pressure vapor side comprising,providing a receptacle for receiving recovered refrigerant and vapor,flowing liquid refrigerant from said high pressure side of said systemto said receptacle and flowing vapor from said receptacle, reducing saidvapor from said receptacle to a first liquid and flowing said firstliquid to said receptacle, flowing vapor from said low pressure side ofsaid system, reducing said vapor from said system to a second liquid andflowing said second liquid to said receptacle, collecting gas from saidfirst liquid and from said second liquid, and periodically exhaustingsaid collected gas to atmosphere.
 65. The method according to claim 64,and detecting the quantity of said collected gas, and precluding saidexhausting of said collected gas to atmosphere until a predeterminedquantity is collected.
 66. The method according to claim 64, andexhausting said collected gas to atmosphere at a controlled flow rate.67. A method of recovering refrigerant from a refrigeration systemhaving a high pressure liquid side and a low pressure vapor sidecomprising, providing a receptacle for receiving recovered refrigerantand vapor, flowing liquid refrigerant from said high pressure side ofsaid system to said receptacle and flowing vapor from said receptacle,reducing said vapor from said receptacle to a first liquid and flowingsaid first liquid to said receptacle, flowing vapor from said lowpressure side of said system, reducing said vapor from said system to asecond liquid and flowing said second liquid to said receptacle,collecting gas from said first liquid and from said second liquid,exhausting said collected gas to atmosphere, stopping said flowing ofvapor from said receptacle during said flowing of vapor from said lowpressure side of said system, monitoring a condition in said receptacleduring said flowing of vapor from said low pressure side and, inresponse to an undesirable condition, stopping said flowing of vaporfrom said low pressure side of said system, and flowing vapor from saidreceptacle, reducing the last named vapor to a liquid and flowing thelast named liquid to said receptacle.
 68. The method according to claim67, wherein said monitored condition is pressure.
 69. The methodaccording to claim 67, and exhausting said collected gas to atmosphereduring said stopping of said flowing of vapor from said low pressureside.
 70. The method according to claim 67, and initiating a time cyclein response to said undesirable condition in said receptacle, andexhausting said collected gas to atmosphere during a portion of saidtime cycle.
 71. The method according to claim 70, and repeating saidtime cycle until said undesirable condition is eliminated.
 72. Themethod according to claim 70, wherein said monitored condition ispressure.
 73. The method according to claim 72, and detecting thequantity of said collected gas, and precluding said exhausting of saidcollected gas to atmosphere until a predetermined quantity is collected.74. The method according to claim 73, and repeating said time cycleuntil said undesirable condition is eliminated.
 75. The method accordingto claim 74, and exhausting said collected gas to atmosphere at acontrolled flow rate.